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Hook up my Nitrogen on suction line at condensing unit,take out schrader valve on liquid line and let nitrogen escape thru open liquid line. Question is when I braze the suction line I know I should wrap service valve with a wet rag,not allowing any water to enter,is my schrader valve and hose safe from heat damage?

Use a heat blocking paste.
It looks like toothpaste.
Block-Heat is one brand, Hot Dam is another.
Wet rags are secondary.
Since water boils at 212, your wet rag will be just a damp rag pretty quickly.
Keep more than one rag handy, in a pail of water.
Put hoses on the access fittings, to keep the water out.
Pay attention to where the other end of the hoses are, so that you don't get them dirty.

put hose on liquid line and braze suction line. them put hose on suction line and braze liquid line
takes a couple more seconds but your hoses will be safe and mose important is a haet block on the valves so you wont melt the seals water most time isnt enough

Keep a sprayer bottle filled with water handy. If you think the wet rag is drying out, shoot it with the water bottle. The hose will keep water out. Pull the shrader. The hose will be fine. Make sure not to flow too much N2 as the pressure will push the slag from the joint ergo a leak.

There is nothing more frightful than ignorance in action....Mark Twain

Originally posted by bwal2 Use a heat blocking paste.
It looks like toothpaste.
Block-Heat is one brand, Hot Dam is another.
Wet rags are secondary.
Since water boils at 212, your wet rag will be just a damp rag pretty quickly.
Keep more than one rag handy, in a pail of water.
Put hoses on the access fittings, to keep the water out.
Pay attention to where the other end of the hoses are, so that you don't get them dirty.

Dang! How long do you take to braze in a joint? I can get it done in less than 30sec, and the wet rag is still really wet when I am done, not to mention my valve never gets hot.... Maybe we are working on differnt stuff...

Brazing multiple joints

when you braze in multiple joints or larger diameter copper tubing the wet rag can get dry very quickly, although I have never had any problems brazing with the wet rag, heat blocker is a nice thing to have on the truck if your company allows you to purchase. Most employers like to save the $10 and give you a bucket and a rag instead.

Dang! How long do you take to braze in a joint? I can get it done in less than 30sec, and the wet rag is still really wet when I am done, not to mention my valve never gets hot.... Maybe we are working on differnt stuff...

HEAT

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Dang! How long do you take to braze in a joint? I can get it done in less than 30sec, and the wet rag is still really wet when I am done, not to mention my valve never gets hot.... Maybe we are working on differnt stuff... [/B][/QUOTE]

It is because their not using enough heat to bring the tempurture up quickly, too little heat too long makes things hot...

Get in and get out... A good torch at the right flame can heat evenly and quicker and lets you quinch the heat before the entire valve is toasting!!!!!!

we had brazing class at work

what do you guys think of stay bright at valves. maker clams the fitting are stronger because the heat is lower and doesnt aneal the fittings so stronger. they say no carbonizing inside tubes because of lower heat. this is not the first time iv heard this. i have a buddy that uses staybright for everything except for joint near the compressor.

Just got back from that job. Removed schrader valves,put on the heat block(toothpaste looking type) and also wrapped valves with wet rag. Hoses on so no water could enter system. Valve bodies still heated up some. Why don't they make the stubs coming off valve longer! Brazing is a little more work than solder but it looks so much stronger. Yes I purged with nitrogen the whole time. Only mess up ....had vacuum pump on for 20 minutes before I realized that the piston was in a little bag next to me. Had to unscrew stub and start again.